diff --git a/Cargo.lock b/Cargo.lock
index af541a227..2f59ae56a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2942,7 +2942,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fe7591b152d20a8a992f8b3a5daf6bc9e38e7fb347e3694ed9238eddc7e57332"
 dependencies = [
  "aes",
- "base64 0.21.4",
  "bitvec",
  "byteorder",
  "ctr",
diff --git a/aggregator/src/aggregator.rs b/aggregator/src/aggregator.rs
index 229ecb138..90a64ad92 100644
--- a/aggregator/src/aggregator.rs
+++ b/aggregator/src/aggregator.rs
@@ -816,7 +816,7 @@ impl<C: Clock> TaskAggregator<C> {
                     2,
                     *bits,
                     *length,
-                    VdafInstance::chunk_size(*length),
+                    VdafInstance::chunk_size(*bits * *length),
                 )?;
                 let verify_key = task.primary_vdaf_verify_key()?;
                 VdafOps::Prio3SumVec(Arc::new(vdaf), verify_key)
diff --git a/aggregator/src/aggregator/aggregation_job_creator.rs b/aggregator/src/aggregator/aggregation_job_creator.rs
index c04eae953..fe0fbb2db 100644
--- a/aggregator/src/aggregator/aggregation_job_creator.rs
+++ b/aggregator/src/aggregator/aggregation_job_creator.rs
@@ -292,7 +292,7 @@ impl<C: Clock + 'static> AggregationJobCreator<C> {
                     2,
                     *bits,
                     *length,
-                    VdafInstance::chunk_size(*length),
+                    VdafInstance::chunk_size(*bits * *length),
                 )?);
                 self.create_aggregation_jobs_for_time_interval_task_no_param::<VERIFY_KEY_LENGTH, Prio3SumVecMultithreaded>(task, vdaf)
                     .await
@@ -411,7 +411,7 @@ impl<C: Clock + 'static> AggregationJobCreator<C> {
                     2,
                     *bits,
                     *length,
-                    VdafInstance::chunk_size(*length),
+                    VdafInstance::chunk_size(*bits * *length),
                 )?);
                 let max_batch_size = *max_batch_size;
                 let batch_time_window_size = *batch_time_window_size;
diff --git a/core/src/task.rs b/core/src/task.rs
index 5826e03c3..2adaca84f 100644
--- a/core/src/task.rs
+++ b/core/src/task.rs
@@ -190,7 +190,7 @@ macro_rules! vdaf_dispatch_impl_base {
                     2,
                     *bits,
                     *length,
-                    janus_core::task::VdafInstance::chunk_size(*length),
+                    janus_core::task::VdafInstance::chunk_size(*bits * *length),
                 )?;
                 type $Vdaf = ::prio::vdaf::prio3::Prio3SumVecMultithreaded;
                 const $VERIFY_KEY_LEN: usize = ::janus_core::task::VERIFY_KEY_LENGTH;
diff --git a/integration_tests/tests/common/mod.rs b/integration_tests/tests/common/mod.rs
index 72d011c27..deced10af 100644
--- a/integration_tests/tests/common/mod.rs
+++ b/integration_tests/tests/common/mod.rs
@@ -284,7 +284,7 @@ pub async fn submit_measurements_and_verify_aggregate(
                 2,
                 *bits,
                 *length,
-                VdafInstance::chunk_size(*length),
+                VdafInstance::chunk_size(*bits * *length),
             )
             .unwrap();
 
diff --git a/interop_binaries/src/bin/janus_interop_client.rs b/interop_binaries/src/bin/janus_interop_client.rs
index 166cbf0fa..96ad8c5c3 100644
--- a/interop_binaries/src/bin/janus_interop_client.rs
+++ b/interop_binaries/src/bin/janus_interop_client.rs
@@ -161,9 +161,13 @@ async fn handle_upload(
 
         VdafInstance::Prio3SumVec { bits, length } => {
             let measurement = parse_vector_measurement::<u128>(request.measurement.clone())?;
-            let vdaf_client =
-                Prio3::new_sum_vec_multithreaded(2, bits, length, VdafInstance::chunk_size(length))
-                    .context("failed to construct Prio3SumVec VDAF")?;
+            let vdaf_client = Prio3::new_sum_vec_multithreaded(
+                2,
+                bits,
+                length,
+                VdafInstance::chunk_size(bits * length),
+            )
+            .context("failed to construct Prio3SumVec VDAF")?;
             handle_upload_generic(http_client, vdaf_client, request, measurement).await?;
         }
 
diff --git a/interop_binaries/src/bin/janus_interop_collector.rs b/interop_binaries/src/bin/janus_interop_collector.rs
index b37b044c4..ccd5e8be5 100644
--- a/interop_binaries/src/bin/janus_interop_collector.rs
+++ b/interop_binaries/src/bin/janus_interop_collector.rs
@@ -345,9 +345,13 @@ async fn handle_collection_start(
         }
 
         (ParsedQuery::TimeInterval(batch_interval), VdafInstance::Prio3SumVec { bits, length }) => {
-            let vdaf =
-                Prio3::new_sum_vec_multithreaded(2, bits, length, VdafInstance::chunk_size(length))
-                    .context("failed to construct Prio3SumVec VDAF")?;
+            let vdaf = Prio3::new_sum_vec_multithreaded(
+                2,
+                bits,
+                length,
+                VdafInstance::chunk_size(nits * length),
+            )
+            .context("failed to construct Prio3SumVec VDAF")?;
             handle_collect_generic(
                 http_client,
                 collector_params,
@@ -567,9 +571,13 @@ async fn handle_collection_start(
         }
 
         (ParsedQuery::FixedSize(fixed_size_query), VdafInstance::Prio3SumVec { bits, length }) => {
-            let vdaf =
-                Prio3::new_sum_vec_multithreaded(2, bits, length, VdafInstance::chunk_size(length))
-                    .context("failed to construct Prio3SumVec VDAF")?;
+            let vdaf = Prio3::new_sum_vec_multithreaded(
+                2,
+                bits,
+                length,
+                VdafInstance::chunk_size(bits * length),
+            )
+            .context("failed to construct Prio3SumVec VDAF")?;
             handle_collect_generic(
                 http_client,
                 collector_params,
diff --git a/tools/src/bin/collect.rs b/tools/src/bin/collect.rs
index aaeb4d826..739738d45 100644
--- a/tools/src/bin/collect.rs
+++ b/tools/src/bin/collect.rs
@@ -467,7 +467,7 @@ where
                 .map_err(|err| Error::Anyhow(err.into()))
         }
         (VdafType::SumVec, Some(length), Some(bits)) => {
-            let vdaf = Prio3::new_sum_vec(2, bits, length, VdafInstance::chunk_size(length))
+            let vdaf = Prio3::new_sum_vec(2, bits, length, VdafInstance::chunk_size(bits * length))
                 .map_err(|err| Error::Anyhow(err.into()))?;
             run_collection_generic(parameters, vdaf, http_client, query, &())
                 .await